Trial consideration and Conclusions Clausole campione

Trial consideration and Conclusions. The laboratories participants to the trial had different backgrounds; either experienced in non-target analysis either novice in the field, attending the screening analysis for the first time. For our group was in absolute the first attempt in such comprehensive non- target analysis, and this fact was reflected in the relative low number of submitted results of non-target compound. The used instrumentation setting was roughly comparable with the rest of the trial’s participants (Table S 2 and Table S 3). The adopted “two-step” protocol was exce lent for the target analysis. In fact, this approach allowed a fast, easy and reliable confirmation of the structure. The unique limitation of the target screening we have experimented was the very limited availability of analytical standards. For the suspect screening the limitation was the non-availability of a database containing specific water contaminants, so that we used vendor’s libraries in which most of the compounds were non likely to be present in river water. Structural investigation using target MS/MS feature was resulted critic to increase the identification level of the structure. Q-TOF system is known for the speed in acquisition and this allows the acquisition of many MS/MS spectra at the same time. Despite this, a partial sensitivity loss was experimented with the increasing number of fragmentation per cycle, thus limiting the overall capability in structural confirmation, especially when analytes were at ultratrace levels. To avoid this drawback, similarly to all the trial participants, we adopted a quite long chromatographic run in order to give a sufficient time to the analyser for performing the MS/MS experiments and having a good peak reconstruction in EIC spectra. In non-target analysis, in addition to the same issues as suspect screening, the generation of a unique and reliable molecular formula seems to be the limiting step. As expressed by most of the participants, non-target analysis require specific software that are non-commercially available able to treat big dataset and produce reliable results. Finally, the non-target screening was tedious and highly time-consuming because, without any previous experience in the field, and the non-availability of specific software required a big amount of manual work. The needing of much more time for the data treating was a common feeling of the trial participants, suggesting that it is currently impossible adopting such non-target approach for the ...